kernel/drivers/rtc, branch linux-5.15.y

rtc: interface: Alarm race handling should not discard preceding error

2026-03-04T12:19:56Z

[ Upstream commit 81be22cd4ace020045cc6d31255c6f7c071eb7c0 ] Commit 795cda8338ea ("rtc: interface: Fix long-standing race when setting alarm") should not discard any errors from the preceding validations. Prior to that commit, if the alarm feature was disabled, or the set_alarm failed, a meaningful error code would be returned to the caller for further action. After, more often than not, the __rtc_read_time will cause a success return code instead, misleading the caller. An example of this is when timer_enqueue is called for a rtc-abx080x device. Since that driver does not clear the alarm feature bit, but instead relies on the set_alarm operation to return invalid, the discard of the return code causes very different behaviour; i.e. hwclock: select() to /dev/rtc0 to wait for clock tick timed out Fixes: 795cda8338ea ("rtc: interface: Fix long-standing race when setting alarm") Signed-off-by: Anthony Pighin (Nokia) Reviewed-by: Esben Haabendal Tested-by: Nick Bowler Link: https://patch.msgid.link/BN0PR08MB6951415A751F236375A2945683D1A@BN0PR08MB6951.namprd08.prod.outlook.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: rx8025: fix incorrect register reference

2025-12-06T21:09:26Z

commit 162f24cbb0f6ec596e7e9f3e91610d79dc805229 upstream. This code is intended to operate on the CTRL1 register, but ctrl[1] is actually CTRL2. Correctly, ctrl[0] is CTRL1. Signed-off-by: Yuta Hayama Fixes: 71af91565052 ("rtc: rx8025: fix 12/24 hour mode detection on RX-8035") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/eae5f479-5d28-4a37-859d-d54794e7628c@lineo.co.jp Signed-off-by: Alexandre Belloni Signed-off-by: Greg Kroah-Hartman

rtc: pcf2127: clear minute/second interrupt

2025-12-06T21:09:24Z

[ Upstream commit a6f1a4f05970664004a9370459c6799c1b2f2dcf ] PCF2127 can generate interrupt every full second or minute configured from control and status register 1, bits MI (1) and SI (0). On interrupt control register 2 bit MSF (7) is set and must be cleared to continue normal operation. While the driver never enables this interrupt on its own, users or firmware may do so - e.g. as an easy way to test the interrupt. Add preprocessor definition for MSF bit and include it in the irq bitmask to ensure minute and second interrupts are cleared when fired. This fixes an issue where the rtc enters a test mode and becomes unresponsive after a second interrupt has fired and is not cleared in time. In this state register writes to control registers have no effect and the interrupt line is kept asserted [1]: [1] userspace commands to put rtc into unresponsive state: $ i2cget -f -y 2 0x51 0x00 0x04 $ i2cset -f -y 2 0x51 0x00 0x05 # set bit 0 SI $ i2cget -f -y 2 0x51 0x00 0x84 # bit 8 EXT_TEST set $ i2cset -f -y 2 0x51 0x00 0x05 # try overwrite control register $ i2cget -f -y 2 0x51 0x00 0x84 # no change Signed-off-by: Josua Mayer Reviewed-by: Bruno Thomsen Link: https://lore.kernel.org/r/20250825-rtc-irq-v1-1-0133319406a7@solid-run.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: interface: Fix long-standing race when setting alarm

2025-10-19T14:21:47Z

commit 795cda8338eab036013314dbc0b04aae728880ab upstream. As described in the old comment dating back to commit 6610e0893b8b ("RTC: Rework RTC code to use timerqueue for events") from 2010, we have been living with a race window when setting alarm with an expiry in the near future (i.e. next second). With 1 second resolution, it can happen that the second ticks after the check for the timer having expired, but before the alarm is actually set. When this happen, no alarm IRQ is generated, at least not with some RTC chips (isl12022 is an example of this). With UIE RTC timer being implemented on top of alarm irq, being re-armed every second, UIE will occasionally fail to work, as an alarm irq lost due to this race will stop the re-arming loop. For now, I have limited the additional expiry check to only be done for alarms set to next seconds. I expect it should be good enough, although I don't know if we can now for sure that systems with loads could end up causing the same problems for alarms set 2 seconds or even longer in the future. I haven't been able to reproduce the problem with this check in place. Cc: stable@vger.kernel.org Signed-off-by: Esben Haabendal Link: https://lore.kernel.org/r/20250516-rtc-uie-irq-fixes-v2-1-3de8e530a39e@geanix.com Signed-off-by: Alexandre Belloni Signed-off-by: Greg Kroah-Hartman

rtc: interface: Ensure alarm irq is enabled when UIE is enabled

2025-10-19T14:21:47Z

commit 9db26d5855d0374d4652487bfb5aacf40821c469 upstream. When setting a normal alarm, user-space is responsible for using RTC_AIE_ON/RTC_AIE_OFF to control if alarm irq should be enabled. But when RTC_UIE_ON is used, interrupts must be enabled so that the requested irq events are generated. When RTC_UIE_OFF is used, alarm irq is disabled if there are no other alarms queued, so this commit brings symmetry to that. Signed-off-by: Esben Haabendal Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250516-rtc-uie-irq-fixes-v2-5-3de8e530a39e@geanix.com Signed-off-by: Alexandre Belloni Signed-off-by: Greg Kroah-Hartman

rtc: x1205: Fix Xicor X1205 vendor prefix

2025-10-19T14:21:40Z

[ Upstream commit 606d19ee37de3a72f1b6e95a4ea544f6f20dbb46 ] The vendor for the X1205 RTC is not Xircom, but Xicor which was acquired by Intersil. Since the I2C subsystem drops the vendor prefix for driver matching, the vendor prefix hasn't mattered. Fixes: 6875404fdb44 ("rtc: x1205: Add DT probing support") Signed-off-by: Rob Herring (Arm) Reviewed-by: Linus Walleij Link: https://lore.kernel.org/r/20250821215703.869628-2-robh@kernel.org Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: remove clear of oscillator stop flag (OSF) in probe

2025-08-28T14:24:26Z

[ Upstream commit 48458654659c9c2e149c211d86637f1592470da5 ] In using CONFIG_RTC_HCTOSYS, rtc_hctosys() will sync the RTC time to the kernel time as long as rtc_read_time() succeeds. In some power loss situations, our supercapacitor-backed DS1342 RTC comes up with either an unpredictable future time or the default 01/01/00 from the datasheet. The oscillator stop flag (OSF) is set in these scenarios due to the power loss and can be used to determine the validity of the RTC data. Some chip types in the ds1307 driver already have OSF handling to determine whether .read_time provides valid RTC data or returns -EINVAL. This change removes the clear of the OSF in .probe as the OSF needs to be preserved to expand the OSF handling to the ds1341 chip type (note that DS1341 and DS1342 share a datasheet). Signed-off-by: Meagan Lloyd Reviewed-by: Tyler Hicks Acked-by: Rodolfo Giometti Link: https://lore.kernel.org/r/1749665656-30108-2-git-send-email-meaganlloyd@linux.microsoft.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: ds1307: handle oscillator stop flag (OSF) for ds1341

2025-08-28T14:24:24Z

[ Upstream commit 523923cfd5d622b8f4ba893fdaf29fa6adeb8c3e ] In using CONFIG_RTC_HCTOSYS, rtc_hctosys() will sync the RTC time to the kernel time as long as rtc_read_time() succeeds. In some power loss situations, our supercapacitor-backed DS1342 RTC comes up with either an unpredictable future time or the default 01/01/00 from the datasheet. The oscillator stop flag (OSF) is set in these scenarios due to the power loss and can be used to determine the validity of the RTC data. This change expands the oscillator stop flag (OSF) handling that has already been implemented for some chips to the ds1341 chip (DS1341 and DS1342 share a datasheet). This handling manages the validity of the RTC data in .read_time and .set_time based on the OSF. Signed-off-by: Meagan Lloyd Reviewed-by: Tyler Hicks Acked-by: Rodolfo Giometti Link: https://lore.kernel.org/r/1749665656-30108-3-git-send-email-meaganlloyd@linux.microsoft.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: rv3028: fix incorrect maximum clock rate handling

2025-08-28T14:24:12Z

[ Upstream commit b574acb3cf7591d2513a9f29f8c2021ad55fb881 ] When rv3028_clkout_round_rate() is called with a requested rate higher than the highest supported rate, it currently returns 0, which disables the clock. According to the clk API, round_rate() should instead return the highest supported rate. Update the function to return the maximum supported rate in this case. Fixes: f583c341a515f ("rtc: rv3028: add clkout support") Signed-off-by: Brian Masney Link: https://lore.kernel.org/r/20250710-rtc-clk-round-rate-v1-6-33140bb2278e@redhat.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin

rtc: pcf8563: fix incorrect maximum clock rate handling

2025-08-28T14:24:12Z

[ Upstream commit 906726a5efeefe0ef0103ccff5312a09080c04ae ] When pcf8563_clkout_round_rate() is called with a requested rate higher than the highest supported rate, it currently returns 0, which disables the clock. According to the clk API, round_rate() should instead return the highest supported rate. Update the function to return the maximum supported rate in this case. Fixes: a39a6405d5f94 ("rtc: pcf8563: add CLKOUT to common clock framework") Signed-off-by: Brian Masney Link: https://lore.kernel.org/r/20250710-rtc-clk-round-rate-v1-5-33140bb2278e@redhat.com Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin